So predictable it felt contrived and drawn out but it was still a good story.

Amos Decker joins his FBI parnter Alex Jamison on a vacation visit to her sister's family in their new location of Baronville PA.

Observing strange flickering of lights leads to a joint investigation of six murders with the local police and the DEA. The more they dig the more danger and death they uncover. Further concussions have Decker's brain misfiring giving a potential problem for future novels.
Robber Barons owning the town of Baronville and hidden treasure were a bit of a stretch.